The various organs of the body are composed of multiple cell types working together. By working together, the different cell types maintain the health the organ and help the organ recover from injury. Consider, for instance, the largest organ of the body, skin.
Skin is an essential multilayer organ. Providing a barrier against pathogens and toxins, as well as synthesizing nutrients such as vitamin D, skin is essential for maintaining an individual's physical health. The integrity of skin is also essential for maintaining one's psychological health. Skin is the most prominent part of an individual's body. Blemishes, scars, wrinkles and perceived imperfections can diminish an individual's self-confidence. Maintaining physical and psychological health, therefore, requires maintaining healthy skin.
Healthy skin comprises layers of different cells supported by a scaffolding of proteins called the extracellular matrix. The extracellular matrix supporting the skin comprises various proteins such as collagen, fibronectin and laminin. These and other structural proteins intertwine and communicate to form the structural and dynamic three-dimensional scaffolding providing skin with its strength and resilience. Cells forming the various layers of skin adhere to the extracellular matrix, and rely on both structural and biologically active signal relaying molecules within the matrix to maintain proper function. During wound healing, cells also use the extracellular matrix as a bridge to migrate into and close wounds. Providing support and pathways for healing, the extracellular matrix is an important structural and biologically active component of healthy skin. As an individual ages, however, the extracellular matrix changes and becomes weakened, leading to the appearance of wrinkles, blemishes and decreased healing.
The extracellular matrix is manufactured and maintained primarily by fibroblasts beneath the skin's surface. Manufacturing and maintaining the biological activity of the extracellular matrix, healthy fibroblasts are essential for healthy skin. Above the fibroblasts, on top of the extracellular matrix, are keratinocytes forming the epidermis. Forming the epidermis, the outer layer of skin, healthy keratinocytes are also essential for the appearance and integrity of skin. Signaling between keratinocytes and immune cells helps to maintain homeostasis of the skin and protect against infections. Accordingly, maintaining healthy skin from its base to its surface requires promoting the health of different cells throughout the layers of skins.
The same is true for other organs of the body. The nervous system, for instance, is composed of various neurons and glial cells. Carrying signals to and from the brain, as well as processing information within the spinal cord and brain, neurons are often thought of as the primary workhorses of the nervous system. Neurons, however, are supported by various glial cells. For instance, astrocytes maintain the health of neurons and help the brain recovery from various injuries, such as stroke. Schwan cells insulate peripheral nerves and help them regenerate after injury. Accordingly, just like the skin, the health and healing of the nervous system requires the promoting the health of different cells.
The liver, another important organ of the body, also relies on multiple cell types to maintain health and healing. Repairing and maintaining the extracellular matrix, stellate cells, for instance, are important for maintaining health and healing.